In the air-cooled internal combustion engines, typically, cooling fins are formed to protrude from the outer peripheries of a cylinder and a cylinder head which are stacked in this order on a crankcase in a protruding manner.
Therefore, where the air-cooled internal combustion engine is installed on a saddle riding vehicle, a common example is that the crankcase is supported by being joined to the body frame (see, e.g., Patent Document 1).